GTT leaky exhaust manifold

[Technohedge]

So last few days the Caldina GT has been showing signs of the common exhaust/turbo manifold leak. (its done 220k) The paperwork i have with the car shows that the previous owner had a 'stripped bolt hole fixed' about 4 years ago. Im presuming that it was leaking then.

Looking at the manifold none of the studs look broken. There seems to be a stud in the block (which isnt used, i presume this was where the new lug was to have been welded on when some manifolds were fixed.) and a threaded hole behind the lug on the far left of the manifold. Whats this threaded hole for that seems unused? There is a lug that sits right over it as if it should be bolted? (it seems to have a thread intact)







Ive heard of clamping the manifold using that free stud. Is there any info on how this can be done?

Im unsure if the manifold has been planed before. Whatever fix was done to this before seems to have lasted it a good 5 years.

cheers guys

[GDII]

In the second photo it looks like the whole stud and nut on the far left is missing causing the leak. Using the spare stud above this would help stop the other problem of GTT warped manifold.

[Technohedge]

yeah i have done a little more research and its supposed to be a 7 stud manifold? (and i only have 6) seems a bit dodgy to not have one at the far end. I have no idea why this is missing with the thread in the block apparently intact, so i shall take your advice sir and try bung in that spare stud

any idea what the thread pitch is as i have no nut with it?

worrying now as to what the original 'fix' was for this as the paperwork clearly shows she had symptoms a while ago and this stud would appear to have been absent for a while...

[Technohedge]

Ok so the missing stud hole is much bigger than the original stud. It must have been drilled and re tapped (possibly helicoiled)

The thread seems to be intact so i may see if i can get some sort of stud into it however i have no idea what the thread will be

Thinking about using that 'extra' available stud to make some sort of clamp up. Has anyone got any info on this as Ive heard of it being done?

cheers

[GDII]

I couldn't tell you what thread pitch and diameter you need but as you have found out that missing one has a bigger hole so it won't be a standard stud. I suspect the fix was to fix that stud but it may have worked it's way out and fallen out and gone MIA. The original GTT exhaust manifold between August 1997 and June 2002 had 6 (EDIT: 7) studs. They revised it later in June 2002 to another manifold part number which I assume is the 7 (EDIT: 8 ) stud version. This manifold is the same as the ST246.

Sorry I can't tell you how to fix this problem with the 6 stud manifold as I haven't done it or read up about it.

EDITED to reflect actual stud number on manifolds.

[Technohedge]

Ok cheers bud, its interesting you say the original manifold was a 6 stud, as thats how many i have in there at the moment? Was there no far left stud at all on the earlier models?

In that case it looks like i have a later model manifold on there but just no stud on there where the extra lug is?

[GDII]

Sorry I got confused with something else. Your manifold has 7 studs where the newer one has 8. In your second photo you have the missing stud with the bigger hole from the previous repair, that should always be there. That stud with nothing on it just to the top right, that is stud number 8 for the late model manifold. The late model manifold has an extra part to the flange with a hole in it for this 8th stud, that's what stops the leak.

[GDII]

This shows the ST246 manifold with the extra stud and different manifold. This is what Toyota did to fix the leaking problem.

[Boosted_162]

IIRC the extra stud was added on late ST215s, the manifolds on late gen 2's and all gen 3's also used the extra stud and ran CT based turbos.

[GDII]

IIRC the extra stud was added on late ST215s, the manifolds on late gen 2's and all gen 3's also used the extra stud and ran CT based turbos.

Yeah the ST215 has the same manifold as the ST246 from June 2002.

[Technohedge]

Thanks for the info guys. so now Im keen to get that missing stud replaced somehow. The hole/thread in it is pretty big, I can start to thread an m14 bolt in to the block then it seems to stick. Im presuming its been helicoiled but then wouldnt the helicoil for the original stud have been much smaller?

And if i was to remove the manifold and redrill etc, I would end up with a massive stud in there?

Part of me wants to just ram an m14 tap into that existing hole and make a stud from a bolt. Then make up a clamp arrangement on the other free stud. Unsure that this will work for longer than 10 seconds tho.

Any thoughts on options?

cheers

[Technohedge]

Ok so i have jammed an m14 stud i made into the hole missing the stud, its in there but i doubt its capable of great things. Im gon make up a clamp to use with the extra stud and see how far this gets me.

Im presuming it will leak again (if indeed this fixes it at all, but have little to lose by trying) so then the plan will be remove the manifold and get the extra lug welded on to use the extra stud, and drill and tap the large hole with the m14 stud in out to m16 and them make up a stud that will go in here with reduced shank so it fits the manifold.

Anyone have any info on who can do the manifold fix local to Auckland?

[GDII]

Make sure you get the manifold planed flat again after welding. It's probably already warped as they tend to do on the early manifolds.

[sergei]

Ok so i have jammed an m14 stud i made into the hole missing the stud, its in there but i doubt its capable of great things. Im gon make up a clamp to use with the extra stud and see how far this gets me.

Im presuming it will leak again (if indeed this fixes it at all, but have little to lose by trying) so then the plan will be remove the manifold and get the extra lug welded on to use the extra stud, and drill and tap the large hole with the m14 stud in out to m16 and them make up a stud that will go in here with reduced shank so it fits the manifold.

Anyone have any info on who can do the manifold fix local to Auckland?

How about something like this:

http://www.theinsertcompany.com/steel_s ... nserts.php

Specifically M12x1.25 inner and M16x1.5 outer.

You can make one yourself buy using M16x1.5 bolt and drilling and tapping correct thread for stock stud.
Then you can fit the insert on lock tight and finger tight the stud into the insert, and then tighten the nut to required torque.

[fivebob]

Doesn't matter what you put in to replace the broken stud, if the manifold is warped, then the stud will break again, increasing size won't increase life.

My guess on the the "repair" goes something like this...

• Manifold warps, breaks stud (possibly due to fatigue from repeated stress cycles).
  
• "Mechanic" tries EasyOut, which breaks off in remains of stud.
  
• Drills out stud off centre (due to remains of EasyOut) and damages thread,
  
• Drills out for bigger stud

Probably didn't even plane the manifold flat.

[Technohedge]

Any ideas on who is best to do the welding/planing on the manifold?

cheers

[Technohedge]

So here it is, my 'fix'


image free hosting

Top stud made up with a clamp of sorts to utilise the free stud and the m14 stud in the lower where it was missing.

So far so good. I wonder how long itll be before im on here asking for help to remove the whole manifold

oh well may as well give it a go wasnt too much time expended

[GDII]

Nice idea for the fix. That might work for a bit but if the manifold has already warped then it is going to start pulling on the studs.
If it was me and knowing about the GTT warped manifold issue then I'd take off the manifold and get if machined flat then put it back on with new gaskets. But that's just me. Your fix is far easier and cheaper if it can work because you don't have to undo everything and get new gaskets for all the other bits you had to take off.
I hope it works for you and you don't have any more issues.

[Technohedge]

yeah i dont have high hopes that its gonna last to be honest, i just thought id give it a shot. If it goes again ill do the whole lot off.

cheers for advice

[RS13]

If the gasket has blown, it can be difficult getting a good seal again no matter how much it's clamped. Loving the temp repair! But probably best to start getting parts required and reading up on the permanent repair.